How to increase Domain Authority Of a website ?

Getting backlinks is really not easy, though many Seo person claims that they could bring Backlinks overninght, which i don't find right, they perhaps talk about black hat SEO , and understanding google algorithm is impossible for me.

 C#Corner has DA of 66 with 16.9K linking domains according to MOZ that is why articles here gets indexed on Google the very moment they published with a good rank, sometimes directly on first page of Google.

Some say Good Content is Key, but i have seen many good content are also unnoticed due to poor backlinks or DA of website.

Any good suggestion will be appreciated.